A small female very pale (5)
I believe the answer is:
ashen
'very pale' is the definition.
(I've seen this in another clue)
'a small female' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'female' becomes 'hen' (female chicken).
'a'+'s'+'hen'='ASHEN'
(Other definitions for ashen that I've seen before include "'Very pale, from shock say (5)'" , "showing signs of anaemia" , "Bloodless" , "Wan, pale" , "Looking pale from illness" .)