Supposed place local resident loses head (8)
I believe the answer is:
putative
'supposed' is the definition.
('putative' can be a synonym of 'supposed')
'place local resident loses head' is the wordplay.
'place' becomes 'put' ('put' can be a synonym of 'place'**).
'local resident' becomes 'native'.
'loses head' means to remove the first letter.
'native' with its first letter taken off is 'ative'.
'put'+'ative'='PUTATIVE'
(Other definitions for putative that I've seen before include "Supposed or reputed" , "Generally considered or reputed to be" , "Supposed, generally considered such" , "Supposed - tie up vat (anag)" , "Supposed or thought to be" .)