Monster seen in bog, recently (4)
I believe the answer is:
ogre
'monster' is the definition.
('ogre' can be a synonym of 'monster')
'in bog recently' is the wordplay.
'in' indicates the answer is hidden within the clue.
'OGRE' is hidden in the letters of 'bog recently'.
'seen' is the link.
(Other definitions for ogre that I've seen before include "One making giant strides" , "One to gobble flesh" , "character in 'Puss in Boots'" , "Cruel and wicked person" , "Terrifying monster" .)