A short sunhat's peak is here (4)
I believe the answer is:
atop
'peak is here' is the definition.
The definition suggests a singular noun but the answer is not.
'a short sunhat's' is the wordplay.
'short' means to remove the last letter.
'sunhat' becomes 'topi' (type of sunhat).
'topi' with its final letter taken away is 'top'.
'a'+'top'='ATOP'
(Other definitions for atop that I've seen before include "in the gods?" , "In superior position" , "in dominant position" , "On the peak" , "Surmounting" .)