Reversing begins to get one in difficulties (7)
I believe the answer is:
straits
'difficulties' is the definition.
(I've seen this in another clue)
'reversing begins to get one in' is the wordplay.
'reversing' says the letters should be written in reverse.
'begins' becomes 'sts' (I've seen this in another clue).
'to get one' becomes 'tiar' (I can't justify this - if you can you should believe this answer much more).
'in' indicates putting letters inside.
'sts' enclosing 'tiar' is 'stiarts'.
'stiarts' back-to-front is 'STRAITS'.
Can you help me to learn more?
(Other definitions for straits that I've seen before include "Narrow channels of the sea joining two larger bodies of water" , "Dire --, rock band" , "... of Magellan, Hormuz" , "Sea passages" , "Difficulties" .)