Hurt one squeezing hard (4)
I believe the answer is:
'hurt' is the definition.
'one squeezing hard' is the wordplay.
'one' becomes 'ace' (ace has a value of one in some card games).
'squeezing' indicates putting letters inside (squeeze can mean hug or embrace).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'ace' enclosing 'h' is 'ACHE'.
(Other definitions for ache that I've seen before include "Longing" , "Twinge" , "yearning" , "Hanker" , "Persistent dull pain" .)