Drab female abandons fuel top Nazi collects (7)
I believe the answer is:
hueless
'drab' is the definition.
'female abandons fuel top nazi collects' is the wordplay.
'female' becomes 'f' (abbreviation).
'abandons' indicates named letters should be taken away.
'top nazi' becomes 'hess' (I've seen this before. I am not sure about the 'top' bit.**).
'collects' is an insertion indicator.
'fuel' with 'f' taken away is 'uel'.
'uel' put inside 'hess' is 'HUELESS'.
(Other definitions for hueless that I've seen before include "White" , "Unobtrusive" .)