Playwright having Jack return with different giant (8)
I believe the answer is:
rattigan
'playwright' is the definition.
(I've seen this before)
'jack return with different giant' is the wordplay.
'jack' becomes 'tar' (both are informal terms for sailor).
'return' is a reversal indicator.
'with' says to put letters next to each other.
'different' indicates anagramming the letters (letters placed in a different order).
'tar' reversed gives 'rat'.
'giant' anagrammed gives 'tigan'.
'rat'+'tigan'='RATTIGAN'
'having' is the link.
(Other definitions for rattigan that I've seen before include "Playfellow" , "Terence --, English playwright" , "20th-century playwright" , "Writer" .)