Unfortunately Len's no hero (6)
I believe the answer is:
nelson
'hero' is the definition.
(I've seen this before)
'unfortunately len's no' is the wordplay.
'unfortunately' is an anagram indicator (a bad or unfortunate spelling).
'lens'+'no'='lensno'
'lensno' is an anagram of 'NELSON'.
(Other definitions for nelson that I've seen before include "Lady Hamilton's seafaring lover" , "British admiral, d. 1805" , "grip" , "British naval hero" , "Nile battle hero" .)