Corrals (4)
'corrals' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pens that I've seen before include "Dashes off" , "Literary thought or reflection" , "stalls" , "Writing implements" , "birds" .)
(Other definitions for encloses that I've seen before include "Fences in or includes with the letter" , "Girdles" , "Enfolds or confines" .)