Charge leaders of illegal group infiltrating island (7)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

I~ G~ in ARRAN; Arran is a large Scottish island visible from both Troon and Turnberry golf courses. I played Turnberry when I was 16 – toughest course I ever encountered. I watched Tom Watson win at Troon in 1982, before watching him at Turnberry in 2007 with my daughter, as he fell agonisingly close of winning again at the age of 59.