Almost run aground close to lighthouse (6)
I believe the answer is:
beacon
'lighthouse' is the definition.
(synonyms)
'almost run aground close' is the wordplay.
I cannot quite see how this works, but
'close' could be 'on' (I've seen this in other clues) and 'on' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'to' is the link.
Can you help me to learn more?
(Other definitions for beacon that I've seen before include "Warning or guiding device" , "Warning, guiding, fire" , "A warning light as on headland" , "Warning light on hill or cliff" , "Guiding light?" .)