Smart carrying it, to avoid becoming an easy target (7,4)
I believe the answer is:
sitting duck
'easy target' is the definition.
'smart carrying it to avoid becoming an' is the wordplay.
I cannot really see how this works, but
'smart' could be 'in' (as in fashionable) and 'in' is located in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found in the answer.
'avoid' could be 'duck' (ducking is a kind of avoiding) and 'duck' is present in the answer.
'an' could be 'i' (Roman numeral for one) and 'i' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for sitting duck that I've seen before include "Obvious target" , "Helpless victim" , "Unmissable target" , "Easy target" , "Potential victim" .)