Some deer I encountered, strangely frightening (5)
I believe the answer is:
eerie
'strangely frightening' is the definition.
(I've seen this before)
'some deer i encountered' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'EERIE' is hidden within 'deer i encountered'.
(Other definitions for eerie that I've seen before include "Uncannily strange" , "Oddly frightening" , "Unnatural" , "Spooky, weird" , "Spectral" .)