Wet weather interrupting sport — test fancy anoraks (13)
I believe the answer is:
trainspotters
'anoraks' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'wet weather interrupting sport test fancy' is the wordplay.
'wet weather' becomes 'rain' (rain is wet weather).
'interrupting' means one lot of letters goes inside another.
'fancy' is an anagram indicator.
'sport'+'test'='sporttest'
'sporttest' anagrammed gives 'tspotters'.
'rain' inserted within 'tspotters' is 'TRAINSPOTTERS'.
Can you help me to learn more?
(Another definition for trainspotters that I've seen is " geeks".)