Gross desire, losing head (4)
I believe the answer is:
earn
'gross' is the definition.
(thesaurus)
'desire losing head' is the wordplay.
'desire' becomes 'yearn' (yearning is a kind of desiring).
'losing head' means to remove the first letter.
'yearn' with its initial letter removed is 'EARN'.
(Other definitions for earn that I've seen before include "Deserve - merit" , "Gain by effort (4)" , "Acquire by ones' effort" , "Twist out of shape" , "and 3: Work for bed and board" .)