Ceiling moulding could be first class or merely pleasant (7)
I believe the answer is:
cornice
'ceiling moulding' is the definition.
'cornice' can be an answer for 'moulding' (cornice is a kind of moulding). I'm not certain of the 'ceiling' bit.
'first class or merely pleasant' is the wordplay.
'first class' becomes 'c' (nst letter of 'class').
'merely pleasant' becomes 'nice' (similar in meaning. I am not sure about the 'merely' bit.).
'c'+'or'+'nice'='CORNICE'
'could be' is the link.
Can you help me to learn more?
(Other definitions for cornice that I've seen before include "Moulding along top of building" , "Ledge of snow overhanging a precipice" , "Ornamental wall moulding" , "Crane-fly" , "decorative feature" .)