Look of love and joy, no end (4)
I believe the answer is:
ogle
'look' is the definition.
(ogling is a kind of looking)
'love and joy no end' is the wordplay.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'and' means one lot of letters go next to another.
'joy' becomes 'glee' (I've seen this before).
'no end' means to remove the last letter.
'glee' with its last letter taken off is 'gle'.
'o'+'gle'='OGLE'
'of' acts as a link.
(Other definitions for ogle that I've seen before include "Gawp" , "Eye flirtatiously" , "Lecherous look" , "Perv" , "Look at amorously" .)