This gate appears to lead to nowhere in particular. It is assumed that it was part of some private access to the shore below, which has since been either washed away, or become overgrown through lack of use, or both. Many of the houses in this area had their own access to the shore, few of which remain. The most obvious of these can be seen when you leave the cliff path on the descent to Drumleck Point (See trailhead references for GC1NO65 Where Bats Dare).
Retrieval of this cache does not require you to leave the cliff path. Please take care to replace it carefully to prevent accidental discovery.