Case for weapon in small taxi seen by poet (8)
I believe the answer is:
scabbard
'case for weapon' is the definition.
(case for a blade)
'small taxi seen by poet' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'taxi' becomes 'cab' (synonyms).
'seen by' means one lot of letters go next to another.
'poet' becomes 'bard' (bard is a kind of poet).
's'+'cab'+'bard'='SCABBARD'
'in' acts as a link.
(Other definitions for scabbard that I've seen before include "Brand protector" , "foil container?" , "One holding a sword" , "Weapon held here" , "foil cover?" .)