The term ALLEY SIGHT can be solved by the three-letter word PIN. An alley is a narrow street or lane, usually located in a city or town. Sight is the ability to see or observe something. Therefore, the term ALLEY SIGHT could refer to the act of looking down an alleyway and seeing what is there. The word PIN could be used to describe the act of looking down an alleyway, as if one were 'pinning' their gaze on the alley.