Section of lintel is somewhat flexible (7)
I believe the answer is:
lissome
'flexible' is the definition.
(I've seen this before)
'section of lintel is somewhat' is the wordplay.
'section of' indicates a hidden word.
'LISSOME' is hidden in the letters of 'lintel is somewhat'.
(Other definitions for lissome that I've seen before include "flexible" , "Slim, supple, graceful" , "Lithe; nimble" , "Oil mess (anag)" , "pliable" .)