Look to accommodate Romeo — pretty active for an old guy (4)
I believe the answer is:
spry
'pretty active for an old guy' is the definition.
(spry can describe an active or lively old person)
'look to accommodate romeo' is the wordplay.
'look' becomes 'spy' (spy can mean to look or see).
'to accommodate' indicates putting letters inside.
'romeo' becomes 'r' (phonetic alphabet: alpha, bravo, charlie etc.).
'spy' enclosing 'r' is 'SPRY'.
(Other definitions for spry that I've seen before include "Moving quickly and lightly" , "'Agile, nimble (4)'" , "Alert" , "'Active and lively, nimble (4)'" , "(Of an old person) lively" .)