S. R. Faruqi:

The theme is new, and it is a superior example of 'affair-evocation'. The construction of both lines is superbly trim. And the pleasure is that the whole idea has not been expressed, as to what is the result of the word of love emerging from the mouth. The beloved becomes annoyed and expels him from her presence; or people burst out laughing; or the Rivals become angry. There are all kinds of possibilities.

The excellence of the theme is in the idea that he's compelled to stop himself from saying a word of love; then, another superb aspect is that restraint is impossible and a word from the heart comes to the lips. The whole second line, and especially ik baat pyaar kii , is a superb example of idiomatic speech.

Another excellence of this verse is that here too Mir has brought the experience of passion close to everyday life, and the lover seems to be a character in our own world. In the fourth divan too he has composed this theme [{1325,6}]:

har chand mai;N ne shauq ko pinhaa;N kiyaa vale
ik aadh ;harf pyaar kaa mu;Nh se nikal gayaa

[although I hid my ardor, still
a few words of love emerged from my mouth]

Both verses are fine, but in the present verse the reference to the present situation gives the affair an immediacy and brings us mentally closer.

FWP:

SETS == EK
MOTIFS
NAMES
TERMS == 'AFFAIR-EVOCATION'

What about that ik ? Was the word/idea that emerged from the speaker's lips a 'single' one, a 'particular' one, a 'unique' one, or an 'excellent' one? Each possibility has its own charms, of course, but the 'single' one has the extra benefit of providing more 'connection' with the first line, for when the speaker is trying desperately to keep his mouth shut, to have only a 'single' word slip out is a very plausible result that increases the realism of the scene. So perhaps we should think of 'single' as a primary meaning, or as the first among equals, with the others hovering around it in a kind of cloud of alternatives.

Note for translation fans: 'What can I do?' is of course a kind of phrase-level translation, as opposed to my usual efforts to come as close to the original words as possible. The reason is that the literal 'What might/would I do?' just doesn't capture the petrifed-phrase colloquial pungency of 'What can I do?-- the English expression that occupies much the same all-purpose semi-ironic shoulder-shrug chunk of conversational territory. So on a scale slightly larger than the grammatical, kyaa karuu;N does indeed correspond to 'What can I do?'.