Monstrous creature periodically incenses Indo-European (6)
I believe the answer is:
nessie
'monstrous creature' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
'periodically incenses indo-european' is the wordplay.
'periodically' means one should take alternating letters (letters must be selected 'every so often').
'indo' becomes 'i' (this could be a standard abbreviation which I don't know about).
'european' becomes 'E' (abbreviation e.g. EU).
The alternate letters of 'incenses' are 'ness'.
'ness'+'i'+'e'='NESSIE'
Can you help me to learn more?
(Other definitions for nessie that I've seen before include "Supposed loch monster" , "Scots loch monster (colloq.)" , "Nickname for a Scottish monster" .)