Imagine being badly armed (5)
I believe the answer is:
dream
'imagine' is the definition.
(dreaming is a kind of imagining)
'badly armed' is the wordplay.
'badly' indicates anagramming the letters (letters in the wrong order).
'armed' is an anagram of 'DREAM'.
'being' is the link.
(Other definitions for dream that I've seen before include "Aspiration" , "person to good to be true" , "Fantasy; ideal" , "Cherished desire" , "Cherished hope; fantasy" .)