Charles writing for openings (6)
I believe the answer is:
chasms
'openings' is the definition.
(I know this)
'charles writing' is the wordplay.
'charles' becomes 'Chas' (shortened form).
'writing' becomes 'ms' (abbreviation for manuscript).
'chas'+'ms'='CHASMS'
'for' is the link.
(Other definitions for chasms that I've seen before include "Deep fissure in the earth" , "Deep openings in the earth's surface" , "Big gaps" , "Deep fissures in the earth" , "Deep gorges, crevasses" .)