Get back in gear with difficulty (6)
I believe the answer is:
regain
'get back' is the definition.
(I've seen this before)
'in gear with difficulty' is the wordplay.
'with difficulty' indicates an anagram.
'in'+'gear'='ingear'
'ingear' anagrammed gives 'REGAIN'.
(Other definitions for regain that I've seen before include "Get back, recover the use of" , "Take back (the Ashes, for example)" , "Win back" , "Possess once more for regina" , "Recover, retrieve" .)