Account for Essex's banks not attractive (7)
I believe the answer is:
explain
'account for' is the definition.
(I've seen this before)
'essex's banks not attractive' is the wordplay.
'banks' means to remove the middle letters (the sides or banks of the word).
'not attractive' becomes 'plain' (I've seen this before).
'essex' with its middle removed is 'ex'.
'ex'+'plain'='EXPLAIN'
(Other definitions for explain that I've seen before include "Interpret" , "Make comprehensible" , "Show the whys and wherefores" , "Elucidate, make clear" , "Pin axle (anag.)" .)