Fruit grower's head to hire once again (9)
I believe the answer is:
greengage
'fruit' is the definition.
(type of plum)
'grower's head to hire once again' is the wordplay.
'head to' says to take the initial letters (I've seen 'heading to' mean this).
'hire once again' becomes 're-engage' (engage or hire again).
The first letter of 'growers' is 'g'.
'g'+'reengage'='GREENGAGE'
(Other definitions for greengage that I've seen before include "Fruit tree" , "Fruit akin to plum" , "Plum-like fruit" , "Greenish-yellow type of plum" , "Variety of plum" .)