Particular paranormal power periodically perceivable (8)
I believe the answer is:
especial
'particular' is the definition.
(synonyms)
'paranormal power periodically perceivable' is the wordplay.
'paranormal power' becomes 'esp' (I've seen this in another clue).
'periodically' means one should take alternating letters (letters must be selected 'every so often').
The alternating letters of 'perceivable' are 'ecial'.
'esp'+'ecial'='ESPECIAL'
(Other definitions for especial that I've seen before include "Over and above what is usually expected" , "Exclusive" , "CIE pleas can turn out to be distinctive" , "noteworthy" , "Spice ale wrongly and be particular" .)