clue;  lead;  key;  handhold;  hold
 foothold;  footing;  toehold;  stepping stone
 recommendation of an influential person
 (by force of) circumstances
 (by force of) circumstances
 covered bridge passageway connecting the backstage (mirror room) to the noh stage
 catching a fishing hook on seaweed, coral, etc. on the seabed or riverbed
 labor productivity unit;  productivity;  production rate;  man hours
 double corner approach (tactic in the game of go)