US soldier tucking into brew in Mobile (5)
I believe the answer is:
agile
'mobile' is the definition.
(thesaurus)
'us soldier tucking into brew' is the wordplay.
'us soldier' becomes 'gi' (I've seen this in other clues).
'tucking into' means one lot of letters goes inside another.
'brew' becomes 'ale' (ale is a kind of brew).
'gi' going inside 'ale' is 'AGILE'.
'in' is the link.
(Other definitions for agile that I've seen before include "Nimble, active" , "Quick and easy-moving" , "Nimble, fleet" , "Flexible" , "Physically quick and nimble" .)