What may be seen in one area close by (4)
I believe the answer is:
near
'close by' is the definition.
(near means close by)
'what may be seen in one area' is the wordplay.
'what may be seen in' indicates the answer is hidden within the clue.
'NEAR' is hidden in the letters of 'one area'.
(Other definitions for near that I've seen before include "Easy to reach - hard to touch!" , "Close at hand" , "Nigh" , "unlikely to spend much?" , "Close in time or space" .)