Old gear shot in arm with ecstasy by tenor (7)
I believe the answer is:
raiment
'old gear' is the definition.
'raiment' can be an answer for 'gear' (I've seen this before). I'm not certain of the 'old' bit.
'shot in arm with ecstasy by tenor' is the wordplay.
'shot' indicates anagramming the letters.
'with' means one lot of letters go next to another.
'ecstasy' becomes 'E' (informal term for the drug).
'by' says to put letters next to each other.
'tenor' becomes 't' ().
'in'+'arm'='inarm'
'inarm' after 'e' is 'einarm'.
'einarm' is an anagram of 'raimen'.
'raimen'+'t'='RAIMENT'
Can you help me to learn more?
(Other definitions for raiment that I've seen before include "investment" , "Old word for fine clothing" , "Wear" , "Clothing (archaic)" , "Am inert (anag) - clothing" .)