Father and mother surround wharf with revolutionary material (6,5)
I believe the answer is:
papier mache
'revolutionary material' is the definition.
'papier-mache' can be an answer for 'material' (papier-mache is a kind of material). I'm not certain of the 'revolutionary' bit.
'father and mother surround wharf' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'and' means one lot of letters go next to another.
'mother' becomes 'mache' (I am not sure about this - if you are sure you should believe this answer much more).
'surround' is an insertion indicator.
'wharf' becomes 'pier' (I've seen this before).
'pa'+'mache'='pamache'
'pamache' going around 'pier' is 'PAPIER-MACHE'.
'with' is the link.
Can you help me to learn more?
(Other definitions for papier mache that I've seen before include "material for craftwork" , "material for moulds" , "Pulp which can be painted when dry" , "Material moulded when wet" .)