Trainee occasionally rents place to surf (8)
I believe the answer is:
internet
'place to surf' is the definition.
(I've seen this before)
'trainee occasionally rents' is the wordplay.
'trainee' becomes 'intern' (I've seen this before).
'occasionally' means one should take alternating letters.
The alternate letters of 'rents' are 'et'.
'intern'+'et'='INTERNET'
(Other definitions for internet that I've seen before include "where PC gets information" , "Vast computer network" , "Link with the Web etc" , "Electronic communication system" , "Source of information" .)