Feeble or weak (5)
I believe the answer is:
frail
I believe this clue is a double definition.
'feeble' is the first definition.
(similar in meaning)
'weak' is the second definition.
(synonyms)
(Other definitions for frail that I've seen before include "Weak, feeble" , "rush" , "Delicate, fragile" , "Weak and infirm" , "Decrepit" .)