Having second thoughts about one making strides (5)
I believe the answer is:
paces
'strides' is the definition.
('pace' can be a synonym of 'stride')
'having second thoughts about one' is the wordplay.
'having second thoughts' becomes 'ps' (I can't explain this - if you can you should give a lot more credence to this answer).
'about' indicates putting letters inside.
'one' becomes 'ace' ('ace' can be a synonym of 'one').
'ps' going around 'ace' is 'PACES'.
'making' acts as a link.
(Other definitions for paces that I've seen before include "Steps or strides" , "Space for steps" , "Single steps" .)