No time for fat girl (3)
I believe the answer is:
sue
'girl' is the definition.
'no time for fat' is the wordplay.
'no' suggests deleting specific letters.
'time for' becomes 't' (I've seen this in other clues).
'fat' becomes 'suet' (suet is a kind of fat).
'suet' with 't' taken out is 'SUE'.
(Other definitions for sue that I've seen before include "take to 10 [COURT] !" , "Bring charges against - girl" , "Take proceedings against (a person)" , "Charge" , "Take court action" .)