Suspicious about English being tired (5)
I believe the answer is:
weary
'being tired' is the definition.
(similar in meaning)
'suspicious about english' is the wordplay.
'suspicious' becomes 'wary' (I've seen this before).
'about' means one lot of letters goes inside another.
'english' becomes 'E' (abbreviation).
'wary' placed around 'e' is 'WEARY'.
(Other definitions for weary that I've seen before include "Exhausted" , "Tired - bored" , "Ready to drop" , "Physically and mentally fatigued" , "Enervated" .)