Female receiving second shot? (4)
I believe the answer is:
dose
'shot?' is the definition.
(I've seen this in another clue)
'female receiving second' is the wordplay.
'female' becomes 'doe' (female deer).
'receiving' is an insertion indicator.
'second' becomes 's' (common abbreviation).
'doe' enclosing 's' is 'DOSE'.
(Other definitions for dose that I've seen before include "Measured amount of medicine" , "Helping of medicine" , "Medicate" , "Medicinal amount" , "Measure of drug" .)