Reflecting? Not Henry VIII (8)
I believe the answer is:
thinking
'reflecting?' is the definition.
(reflecting is a kind of thinking)
'not henry viii' is the wordplay.
I cannot quite understand how this works, but
'henry' could be 'king' (Henry VIII etc) and 'king' is located in the answer.
The remaining letters 'thin' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
(Other definitions for thinking that I've seen before include "giving opinion" , "Pondering" , "Fancying" , "Rational" , "Cogitating" .)