Increasingly aristocratic, avoiding hard question (5)
I believe the answer is:
poser
'question' is the definition.
(a poser is a difficult question)
'increasingly aristocratic avoiding hard' is the wordplay.
'increasingly aristocratic' becomes 'posher' (posh can mean aristocratic or upper-class).
'avoiding' is a deletion indicator.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'posher' with 'h' taken out is 'POSER'.
(Other definitions for poser that I've seen before include "Attitudiniser" , "Baffling question or problem" , "Problem set by the model" , "Exhibitionist" , "Spore raises a difficult question" .)