tighten

[1]	tighten down/up , fasten , anchor , fasten , fix , tense , secure
[2]	make tighter/tenser/stronger , strengthen
[3]	tighten up , stiffen , tighten up , make more rigorous/strict/stringent/severe/restrictive , close gaps in , constrain
[4]	reduce , tighten up , tauten , stiffen , tense , close