Support turned back in time to give shelter (7)
I believe the answer is:
harbour
'shelter' is the definition.
(harbouring is a kind of sheltering)
'support turned back in time' is the wordplay.
'support' becomes 'bra' (a support for the breasts).
'turned back' says the letters should be written backwards.
'in' is an insertion indicator.
'time' becomes 'hour' (hour is a kind of time).
'bra' backwards is 'arb'.
'arb' put within 'hour' is 'HARBOUR'.
'to give' is the link.
(Other definitions for harbour that I've seen before include "mole" , "Conceal" , "Protected mooring" , "what a master may overlook?" , "Dock" .)