Little girl I had when small (3)
I believe the answer is:
dot
'little girl' is the definition.
(I've seen this before)
'i had when small' is the wordplay.
I cannot quite see how this works, but
'had' could be 'd' (in contractions e.g. 'I'd', 'you'd' etc) and 'd' is present in the answer.
The remaining letters 'ot' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for dot that I've seen before include "Cotton, say" , "Marriage portion; spot" , "Small round spot" , "Flyspeck: period in a web address" , "'Spot, tiny mark (3)'" .)