Space with endorsement, say, having turned picture (8)
I believe the answer is:
envisage
'picture' is the definition.
(I know that picture is a more specific form of the action envisage)
'space with endorsement say having turned' is the wordplay.
'space' becomes 'en' (in printing, a space as wide as a letter 'n').
'with' is a charade indicator (letters next to each other).
'endorsement' becomes 'visa' (visa is a kind of endorsement).
'say' becomes 'eg' (both can mean for example).
'having turned' shows that the letters should be reversed in order.
'eg' reversed gives 'ge'.
'en'+'visa'+'ge'='ENVISAGE'
(Other definitions for envisage that I've seen before include "Visualise - vine's age (anag)" , "Mentally picture" , "Form a mental image of" , "Picture in one's mind" , "Conceive of, imagine" .)