Interrupted by a military policeman, get away clean with this? (7)
I believe the answer is:
shampoo
'clean with this?' is the definition.
(shampoo cleans your hair)
'interrupted by a military policeman get away' is the wordplay.
'interrupted by' means one lot of letters goes inside another.
'military policeman' becomes 'MP' (synonyms).
'get away' becomes 'shoo' (I've seen this before).
'a'+'mp'='amp'
'amp' inserted within 'shoo' is 'SHAMPOO'.
(Other definitions for shampoo that I've seen before include "Cleaning fluid" , "Hair or carpet cleaner" , "Soap for washing hair" , "Hair-cleansing agent" , "Hair lotion" .)