To fix up some tours, there are difficulties (7)

'difficulties' is the definition.
(rigour is a kind of difficulty)

'to fix up some tours there' is the wordplay.
'to fix' means one lot of letters goes inside another (inserted letters are fixed in place).
'some' suggests taking the first letters.
'tours there' becomes 'rigors' (I can't justify this - if you can you should believe this answer much more).
The first letter of 'up' is 'u'.
'u' put inside 'rigors' is 'RIGOURS'.

'are' is the link.

Can you help me to learn more?