Six-footer encountered in verse? (9)
I believe the answer is:
hexameter
This clue is a double definition.
'six-footer' is the first definition.
(line of poetry containing six metric feet)
'verse?' is the second definition.
(hexameter is a kind of verse)
'encountered in' acts as a link.
(Other definitions for hexameter that I've seen before include "line of poetry" , "Exeter ham? (anag)" , "Verse line of six metrical feet" .)