Puts up with second-class, surrounded by assistants (6)
I believe the answer is:
'puts up with' is the definition.
('abide' can be a synonym of 'put up with')
'second-class surrounded by assistants' is the wordplay.
'second-class' becomes 'b' (**).
'surrounded by' means one lot of letters goes inside another.
'assistants' becomes 'aides' (aide is a kind of assistant).
'b' put into 'aides' is 'ABIDES'.
(Other definitions for abides that I've seen before include "Dwells (archaic)" , "Lives, dwells" , "survives" , "Dwells or tolerate" , "Puts up with something or somebody unpleasant" .)