The weak will not succeed without the right leadership (5)
I believe the answer is:
frail
'the weak' is the definition.
(I've seen this before)
'not succeed without the right leadership' is the wordplay.
'not succeed' becomes 'fail' ('fail' is the opposite to 'succeed').
'without' is an insertion indicator ('without' can be similar in meaning to 'outside').
'leadership' suggests taking the first letters.
The first letter of 'right' is 'r'.
'fail' going around 'r' is 'FRAIL'.
'will' is the link.
(Other definitions for frail that I've seen before include "American woman" , "Easily destroyed" , "Basket made of rushes" , "rush" , "Weak, feeble" .)