Believed sheep to be among ruminants heading west (7)
I believe the answer is:
reputed
'believed' is the definition.
(reputing is a kind of believing)
'sheep to be among ruminants heading west' is the wordplay.
'sheep' becomes 'tup' (tup is a kind of sheep).
'to be among' indicates putting letters inside.
'ruminants' becomes 'deer' (deer are a type of ruminant).
'heading west' says the letters should be written in reverse.
'tup' going inside 'deer' is 'detuper'.
'detuper' written backwards gives 'REPUTED'.
(Other definitions for reputed that I've seen before include "Erupted (anag)" , "Supposed" , "Rumoured, reckoned" , "Generally believed (to be the case)" , "Alleged" .)