Extremely short park official — an unfamiliar figure (8)
I believe the answer is:
stranger
'an unfamiliar figure' is the definition.
(I've seen this before)
'extremely short park official' is the wordplay.
'extremely' suggests removing the centre (only the extremes of the word are used).
'park official' becomes 'ranger' (I've seen this before).
'short' with its centre taken out is 'st'.
'st'+'ranger'='STRANGER'
(Other definitions for stranger that I've seen before include "More curious or unfamiliar" , "someone making nuisance call?" , "'Weirder, odder (8)'" , "unfamiliar figure" , "visitor" .)