The pensioners hector like the devil (3,5)
I believe the answer is:
old harry
'the devil' is the definition.
(I've seen this before)
'the pensioners hector' is the wordplay.
'the pensioners' becomes 'old' (I can't justify this - if you can you should believe this answer much more).
'hector' becomes 'harry' (I've seen this before).
'old'+'harry'='OLD HARRY'
'like' acts as a link.
Can you help me to learn more?
(Other definitions for old harry that I've seen before include "Evil character" , "The Devil" .)