Member of Parliament is hard and solemn (6)
I believe the answer is:
owlish
'solemn' is the definition.
(I've seen this before)
'member of parliament is hard' is the wordplay.
'member of parliament' becomes 'owl' ('parliament' is the collective noun for 'owl').
'hard' becomes 'h' (abbreviation used in pencil classifications).
'owl'+'is'+'h'='OWLISH'
'and' acts as a link.
(Other definitions for owlish that I've seen before include "solemn and wise in appearance?" , "Solemn, wise; like a bird" , "Having appearance like wise old bird" .)