Joshua selfishly holds back Abraham's grandson (4)
I believe the answer is:
esau
'abraham's grandson' is the definition.
(I've seen this in another clue)
'joshua selfishly holds back' is the wordplay.
'holds' indicates a hidden word.
'back' says the letters should be written backwards.
'uase' is hidden in the letters of 'joshua selfishly'.
'uase' written backwards gives 'ESAU'.
(Other definitions for esau that I've seen before include "wronged brother" , "Hairy brother to Jacob in Bible" , "scriptural character" , "Big Brother" , "Biblical character who sold birthright for pottage" .)