Dream of one American soldier cutting hair (7)
I believe the answer is:
imagine
'dream of' is the definition.
(I've seen this before)
'one american soldier cutting hair' is the wordplay.
'one' becomes 'i' (Roman numeral).
'american soldier' becomes 'gi'.
'cutting' indicates putting letters inside (some letters cut their way into a word).
'hair' becomes 'mane' (I have seen 'Long hair ' mean 'mane' so perhaps 'hair' could also mean 'mane').
'gi' inserted within 'mane' is 'magine'.
'i'+'magine'='IMAGINE'
(Other definitions for imagine that I've seen before include "that Lennon composed" , "John Lennon hit" , "Conjure up in mind,fancy" , "Picture, conceive" , "Conjure up in mind, visualise" .)