Military display rubbish also (6)
I believe the answer is:
tattoo
'military display' is the definition.
(I've seen this before)
'rubbish also' is the wordplay.
'rubbish' becomes 'tat' (I've seen this before).
'also' becomes 'too' ('too' can be a synonym of 'also').
'tat'+'too'='TATTOO'
(Other definitions for tattoo that I've seen before include "piercing?" , "Design on skin - military show" , "Edinburgh military parade" , "Military display - picture on the skin" , "one has to beat" .)