Cloud and rain, finally -- I'm taking public transport (6)
I believe the answer is:
nimbus
'cloud' is the definition.
(nimbus is a kind of cloud)
'rain finally i'm taking public transport' is the wordplay.
'finally' says to take the final letters.
'taking' means one lot of letters go next to another.
'public transport' becomes 'bus' (bus is a kind of public transport).
The last letter of 'rain' is 'n'.
'n'+'im'+'bus'='NIMBUS'
'and' is the link.
(Other definitions for nimbus that I've seen before include "A rain-cloud or a halo" , "A black rain cloud" , "it could bring rain" , "Dirty cloud; saintly light" , "Bums in (anag)" .)