One often used bombs after Franco originally settled in (5,4,4)

'settled in' is the definition.
(to find one's feet is to settle in or fit in)

'one often used bombs after franco originally' is the wordplay.
'bombs' indicates anagramming the letters.
'after' says to put letters next to each other.
'originally' indicates taking the first letters.
The first letter of 'franco' is 'f'.
'one'+'often'+'used'='oneoftenused'
'oneoftenused' with letters rearranged gives 'oundonesfeet'.
'oundonesfeet' after 'f' is 'FOUND ONES FEET'.