US engine carrying on regardless? (8)
I believe the answer is:
unseeing
'regardless?' is the definition.
(I've seen this before)
'us engine carrying on' is the wordplay.
'carrying on' indicates an anagram (carry on can mean to mess around).
'us'+'engine'='usengine'
'usengine' anagrammed gives 'UNSEEING'.
(Other definitions for unseeing that I've seen before include "regardless?" , "Blind" .)