Oh, endless joy to behold with desire (4)
I believe the answer is:
ogle
'behold with desire' is the definition.
(to ogle is to stare at someone lasciviously)
'oh endless joy' is the wordplay.
'oh' becomes 'o'.
'endless' means to remove the last letter.
'joy' becomes 'glee' (I've seen this before).
'glee' with its last letter taken off is 'gle'.
'o'+'gle'='OGLE'
'to' is the link.
(Other definitions for ogle that I've seen before include "Look at inappropriately" , "Perv" , "Stare at lecherously" , "Amorous glance" , "Amorous stare" .)