What Tom possibly recalled, short hirsute growth (5)
I believe the answer is:
tache
'short hirsute growth' is the definition.
(short for moustache; 'short' asks for an abbreviation)
'what tom possibly recalled' is the wordplay.
'what' becomes 'eh' (sound used to ask 'what?' or 'pardon?').
'tom possibly' becomes 'cat' (a tom is a male cat).
'recalled' shows that the letters should be reversed in order.
'eh'+'cat'='ehcat'
'ehcat' written backwards gives 'TACHE'.
(Other definitions for tache that I've seen before include "Some bristles" , "Whiskers (informal)" , "facial hair" , "Facial ornament" , "show on one's face" .)