Bit strange having soldiers on square (7)
I believe the answer is:
oddment
'bit' is the definition.
(an oddment is a bit or fragment)
'strange having soldiers on square' is the wordplay.
'strange' becomes 'odd' (I've seen this in another clue).
'having' says to put letters next to each other.
'soldiers' becomes 'men' (men can mean a group of soldiers).
'on' says to put letters next to each other.
'square' becomes 't' (a T-Square is a technical drawing instrument).
'odd'+'men'+'t'='ODDMENT'
(Other definitions for oddment that I've seen before include "Leftover piece" , "Leftover item" , "Remnant" , "Scrap" , "Piece left over, no match" .)